Several types of semiconductor devices include semiconductor dies having active devices on a front surface of the die and bond pads or other connective terminals on the opposite side of the die. For example, imaging dies can include image sensors located on a front surface of the die and bond pads for electrically coupling the sensors to other circuit elements. The bond pads are positioned on the back surface of the die to prevent them from interfering with the operation of the sensors, and/or to take advantage of the available surface area at the back surface. Through-wafer interconnects (TWIs) are used to conduct electrical signals from the sensors and associated circuitry, through the die to the bond pads at the back surface. The TWIs are typically formed by making a blind via in the die, filling the via with solder, and then grinding the back surface of the die to expose the blind end of the via, which is used to form the bond pad. A solder ball can then be attached to the bond pad and can be reflowed to couple the die to external devices. In other embodiments, the via can be made to extend entirely through the die without the need for a backgrinding process.
FIG. 1A schematically illustrates a representative etchant chamber 90 configured in accordance with the prior art and used to form vias in a plurality of workpieces 60. The workpieces 60 can be appropriately masked and then positioned side-by-side or otherwise arranged in the etchant chamber 90. The flow of an etchant through the etchant chamber 90 produces vias in the workpieces 60. FIG. 1B schematically illustrates a representative first workpiece 60a having blind holes 63a, and FIG. 1C schematically illustrates a representative second workpiece 60b having through-holes 63b. Before the holes shown in FIGS. 1B and 1C are further processed to form completed vias, they are cleaned. In the case of the blind holes 63a shown in FIG. 1B, the first workpiece 60a is placed in an etchant chamber or other generally similar chamber and exposed to dry-etch chemicals to clean the blind holes 63a. In the case of the through-holes 63b shown in FIG. 1C, the second workpiece 60b is typically positioned in a liquid bath 91 (shown schematically in FIG. 1D) along with other similar workpieces to remove contaminants from the through-holes 63b. 
While the foregoing processes have been used in a variety of contexts to produce workpieces having suitable characteristics, there is a continual need in the industry to improve both the quality of the finished workpieces and the efficiency with which such workpieces are produced. The following disclosure describes systems and processes that meet these needs.